06 Rainwater Harvesting Checklist Spec. No 6 - FINAL

8/15/2019 06 Rainwater Harvesting Checklist Spec. No 6 - FINAL

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DEPARTMENT OF PUBLIC WORKSSWM FACILITYPLAN REVIEW COMMENTS

RAINWATERHARVESTING

Project Name ......................................................................................................................................................POD!SUB " .........................................................................................................................................................Date Rece#$e% &' P(&)#c Wor*+,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,BMP I%e-t#.#er,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

The design, construction, and maintenance of stormwater management facilities are governed by thespecifications included in Section 9.4 of the Henrico County Environmental Compliance anual. The followingchec!list only identifies the information and details that must be included in the S" plan.

RAINWATER HARVESTING /mar* t0e a11ro1r#ate co-.#2(rat#o- t0at #+ &e#-2 re$#e3e%4Co-.#2(rat#o- 5 #ear$round indoor use with optional seasonal outdoor use.Co-.#2(rat#o- 6 Seasonal outdoor use and approved year$round secondary runoff reduction practice%

&ooftop 'isconnection icro$bioretention(egetated )ilter Strip *rban +ioretentionrass Channel 'ry Swale

-nfiltration or icro$infiltration *nderground infiltration soa!$away pitCo-.#2(rat#o- 7 #ear$round indoor use, seasonal outdoor irrigation, and non$seasonal treatment in asecondary runoff reduction practices%

&ooftop 'isconnection icro$bioretention(egetated )ilter Strip *rban +ioretentionrass Channel 'ry Swale-nfiltration or icro$infiltration *nderground infiltration soa!$away pit

MINIMUM DESIGN CRITERIA. Credit is only available for dedicated year$round drawdown/demand for the water through 0 1 internal

use, or 021 irrigation and/or treatment in a secondary practice.

2. The rainwater harvesting system must be designed with si3 primary components% roof surface,collection and conveyance system, pre$screening, storage tan!, distribution system, and overflowmechanism.

ADDITIONAL COMMENTS:•

PLAN RE8UIREMENTS. 5rovide a narrative describing all assumptions made in the design as well as the purpose for which the

harvested rainwater will be used consistent with the appropriate design configuration and documentingwater demand.

4. 5rovide a plan view identifying and providing sufficient details to construct the following si3 primarycomponents of the rainwater harvesting system%

&oof surface, specifying materialCollection and conveyance system, specifying slopes, si6es, and materials, as supported bythe appropriate hydraulic calculations to ensure conveyance of the design storms5re$screening and first flush diverters

5re$filtration devices such as leaf screens and gutter guards must be specified7The first 8.82 8.8: inches of rooftop runoff must be diverted from the storage tan!for larger tan! systems.

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Storage tan!5rovide tan! volume with allowances for dead storage and air gap at the top7Tan! shape or configuration and dimensions7Tan! material7

;ppropriate tan! base or foundation design7unicipal water supply connection details, if applicable.

'istribution systemThe distribution system must be labeled as non$potable.5rovide bac!flow prevention for any cross$connections to a municipal water supply

; drain plug or cleanout sump draining to a pervious area must be designed to allow

the system to be completely emptied.. -dentify underground utilities and potential conflicts, as well as, any other obstructions.:. 5rovide profiles, section views, and details dimensioning the system and, as appropriate, the system

components.?. The plans must clearly indicate that the S" facility has been designed in accordance with Section

9.4.: 0&ainwater Harvesting1 of the Henrico County Environmental Compliance anual.


COMPUTATIONS@. 5rovide appropriate design calculations, as follows%

5rovide storage tan! volume calculations based on the water demand and stormwater treatment volume credit obAectives.5rovide the Cistern 'esign Spreadsheet 0C'S1 found athttp%//www.vwrrc.vt.edu/swc/Bon5roprietary+ 5s.html .)or underground tan!s, provide appropriate load calculations 0e.g., in$situ soil loads, vehicles,pedestrians, etc .1)or underground tan!s, provide appropriate buoyancy calculations, or document the tan! is

situated above the water table5rovide the re=uired hydraulic head based on the ultimate use of the harvested water State all assumptions and coefficients used5rovide routing computations


MAINTENANCE

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http://www.vwrrc.vt.edu/swc/NonProprietaryBMPs.htmlhttp://www.vwrrc.vt.edu/swc/NonProprietaryBMPs.html


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9. ; aintenance ;greement is re=uired, identifying the person or organi6ation responsible for maintenance and authori6ing access for inspections and maintenance.

8. 5rovide a summary of the long term maintenance re=uirements for the S" facility on the S" plan.. -nspections re=uired by the aintenance ;greement must be conducted by 1 a person who is licensed

as a professional engineer, architect, landscape architect, or land surveyor pursuant to Sec. >4. $488 etse=. of the Code of (irginia7 21 a person who wor!s under the direction and oversight of a licensedprofessional engineer, architect, landscape architect, or land surveyor7 or 1 a person who holds aStormwater -nspector or Stormwater Combined ;dministrator certificate of competence from the State"ater Control +oard.


ACCESS AND LOCATION2. *nderground systems must be designed with a standard si6e manhole or e=uipment opening and can

be loc!ed to prevent unwanted access.. The underground tan!s must be set at least 8 feet from any building.4. The cistern overflow devices must be designed to avoid causing ponding or soil saturation within 8

feet of building foundations.


CONSTRUCTION>. 5rovide construction notes that specify the following re=uirements, at a minimum%

The tan! will be installed according to the manufacturer s specifications7 ;ll downspouts or roof drains are routed to pre$screening devices and first flush diverters7

os=uito screens will be installed on all openings7The overflow device will be installed and directed as shown on the plans7The catchment area and overflow area will be stabili6ed7The secondary runoff reduction practice0s1 will be installed.

:. The se=uence of construction must address the S" facility installation and appropriate inspections,including% initial site preparation, e3cavation/grading, and installation of the emban!ment, principaloutlet structure, and emergency spillway. "e recommend the County staff be involved in theseinspections.

?. The se=uence of construction must clearly state that a construction record drawing and certification thatthe stormwater management facility has been constructed in accordance with the approved plan mustbe submitted to the County and approved prior to Environmental Compliance +ond 0EC+1 release.

ADDITIONAL COMMENTS:

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Re$#e3e% &' ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Date Re$#e3e% ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

P0o-e N(m&er ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

July 2014

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Documents

06 Rainwater Harvesting Checklist Spec. No 6 - FINAL